/*
 * jdbc-trace-wrapper
 * Copyright (C) 2010. The jdbc-trace-wrapper Project
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package nz.jdbcwrapper;

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * This class extends a Print-Writer so that the the output file can be rolled
 * over.  If the filename contains a Date format specified within the file name,
 * for example "output-{yyyy-MM-dd}.log", then the log file will be closed and
 * a new one opened when the date-format string would change.
 *
 * The date format is interpreted based on the default time-zone which introduces
 * cute complexities like one day per year being 23 hours long and another being
 * 25 hours long.  Only time-zones that are a multiple of half-an-hour are
 * correctly handled.  Other time-zones may not be rolled over at precisely
 * the right time.
 *
 * The log file is reopened at the following frequency:
 * <ul>
 * <li>each second if the date-format contains the "s" character</li>
 * <li>each minute if the date-format contains the "m" character (but not "s")</li>
 * <li>each half-hour if the date-format exists but does not contain "m" or "s"</li>
 * <li>never if no date-format in {...} is included in the file name</li></ul>
 *
 *
 * User: AdrianP
 * Date: 3/11/2006
 * Time: 09:24:34
 */
public class RollingPrintWriter extends PrintWriter {
    public static final long SECOND    = 1000L;
    public static final long MINUTE    = 60L * SECOND;
    public static final long HALF_HOUR = 30L * MINUTE;

    /**
     * Pattern for rolling file name occurs within {...}
     */
    private static Pattern FORMAT_PATTERN = Pattern.compile("\\{([^}]*)\\}");

    /**
     * File name pattern as passed in constructor
     */
    final String fileNamePattern;

    /**
     * Matcher that will find the {...} pattern in the name passed.
     */
    final Matcher nameMatcher;

    /**
     * Format object based on string found in {...}
     */
    final SimpleDateFormat fileNameFormat;

    /**
     * Current rolling file name with pattern expanded and inserted.
     * Same as fileNamePattern if no pattern passed in.
     */
    String currentFileName;

    /**
     * Whether a {...} section was found.  If not, continuously
     * write to the same file.
     */
    final boolean isRolling;

    /**
     * Interval to close and reopen output using updated pattern
     */
    final long checkInterval;

    /**
     * Time when next file name rollover is due.  Current file will be
     * closed when the first subsequent write is attempted.
     */
    long rollOver;

    /**
     * PrintWriter of current output file.
     */
    PrintWriter currentWriter;

    /**
     * Whether any error has occurred in PrintWriter.
     */
    boolean trouble = false;


    public RollingPrintWriter(String fileNamePattern) throws IOException {
        super(new StringWriter());
        this.fileNamePattern = fileNamePattern;
        nameMatcher = FORMAT_PATTERN.matcher(fileNamePattern);

        isRolling = nameMatcher.find();
        if (isRolling) {
            String format = nameMatcher.group(1);
            fileNameFormat = new SimpleDateFormat(format);
            if (format.matches(".*s.*"))
                checkInterval = SECOND;
            else if (format.matches(".*m.*"))
                checkInterval = MINUTE;
            else
                checkInterval = HALF_HOUR;
            open(System.currentTimeMillis());
        }
        else {
            checkInterval = 0L;
            fileNameFormat = null;
            currentWriter = new PrintWriter(
                new BufferedWriter(new FileWriter(fileNamePattern, true)), true);
        }
    }

    /**
     * Open a new rolling file.
     * @param now
     * @throws IOException
     */
    private void open(long now) throws IOException {
        rollOver = (now + checkInterval) / checkInterval * checkInterval;
        String date = fileNameFormat.format(new Date(now));

        StringBuffer replacement = new StringBuffer();
        if (nameMatcher.find(0))
            nameMatcher.appendReplacement(replacement, date);
        nameMatcher.appendTail(replacement);
        currentFileName = replacement.toString();
        currentWriter = new PrintWriter(
            new BufferedWriter(new FileWriter(currentFileName, true)), true);
    }

    private void ensureOpen() throws IOException {
        if (currentWriter == null)
            throw new IOException("Stream closed");
        if (!isRolling)
            return;
        long now = System.currentTimeMillis();
        if (now < rollOver)
            return;

        currentWriter.close();
        open(now);
    }

    /**
     * Flush the stream.
     * @see #checkError()
     */
    public void flush() {
        try {
            synchronized (lock) {
                ensureOpen();
                currentWriter.flush();
            }
        }
        catch (IOException x) {
            trouble = true;
        }
    }

    /**
     * Close the stream.
     * @see #checkError()
     */
    public void close() {
        synchronized (lock) {
            if (currentWriter == null)
                return;
            currentWriter.close();
            trouble |= currentWriter.checkError();
            currentWriter = null;
        }
    }

    /**
     * Flush the stream if it's not closed and check its error state.
     * Errors are cumulative; once the stream encounters an error, this
     * routine will return true on all successive calls.
     *
     * @return True if the print stream has encountered an error, either on the
     * underlying output stream or during a format conversion.
     */
    public boolean checkError() {
        if (currentWriter != null)
            flush();
        return trouble;
    }

    /** Indicate that an error has occurred. */
    protected void setError() {
        trouble = true;
    }


    /*
     * Exception-catching, synchronized output operations,
     * which also implement the write() methods of Writer
     */

    /**
     * Write a single character.
     * @param c int specifying a character to be written.
     */
    public void write(int c) {
        try {
            synchronized (lock) {
                ensureOpen();
                currentWriter.write(c);
            }
        } catch (IOException e) {
            trouble = true;
        }
    }

    /**
     * Write a portion of an array of characters.
     * @param buf Array of characters
     * @param off Offset from which to start writing characters
     * @param len Number of characters to write
     */
    public void write(char buf[], int off, int len) {
        try {
            synchronized (lock) {
                ensureOpen();
                currentWriter.write(buf, off, len);
            }
        }
        catch (IOException x) {
            trouble = true;
        }
    }

    /**
     * Write an array of characters.  This method cannot be inherited from the
     * Writer class because it must suppress I/O exceptions.
     * @param buf Array of characters to be written
     */
    public void write(char buf[]) {
        write(buf, 0, buf.length);
    }

    /**
     * Write a portion of a string.
     * @param s A String
     * @param off Offset from which to start writing characters
     * @param len Number of characters to write
     */
    public void write(String s, int off, int len) {
        try {
            synchronized (lock) {
                ensureOpen();
                currentWriter.write(s, off, len);
            }
        }
        catch (IOException x) {
            trouble = true;
        }
    }

    /**
     * Write a string.  This method cannot be inherited from the Writer class
     * because it must suppress I/O exceptions.
     * @param s String to be written
     */
    public void write(String s) {
        write(s, 0, s.length());
    }

    private void newLine() {
        try {
            synchronized (lock) {
                ensureOpen();
                currentWriter.println();
            }
        }
        catch (IOException x) {
            trouble = true;
        }
    }


    /* Methods that do not terminate lines */

    /**
     * Print a boolean value.  The string produced by <code>{@link
     * java.lang.String#valueOf(boolean)}</code> is translated into bytes
     * according to the platform's default character encoding, and these bytes
     * are written in exactly the manner of the <code>{@link
     * #write(int)}</code> method.
     *
     * @param      b   The <code>boolean</code> to be printed
     */
    public void print(boolean b) {
        write(b ? "true" : "false");
    }

    /**
     * Print a character.  The character is translated into one or more bytes
     * according to the platform's default character encoding, and these bytes
     * are written in exactly the manner of the <code>{@link
     * #write(int)}</code> method.
     *
     * @param      c   The <code>char</code> to be printed
     */
    public void print(char c) {
        write(c);
    }

    /**
     * Print an integer.  The string produced by <code>{@link
     * java.lang.String#valueOf(int)}</code> is translated into bytes according
     * to the platform's default character encoding, and these bytes are
     * written in exactly the manner of the <code>{@link #write(int)}</code>
     * method.
     *
     * @param      i   The <code>int</code> to be printed
     * @see        java.lang.Integer#toString(int)
     */
    public void print(int i) {
        write(String.valueOf(i));
    }

    /**
     * Print a long integer.  The string produced by <code>{@link
     * java.lang.String#valueOf(long)}</code> is translated into bytes
     * according to the platform's default character encoding, and these bytes
     * are written in exactly the manner of the <code>{@link #write(int)}</code>
     * method.
     *
     * @param      l   The <code>long</code> to be printed
     * @see        java.lang.Long#toString(long)
     */
    public void print(long l) {
        write(String.valueOf(l));
    }

    /**
     * Print a floating-point number.  The string produced by <code>{@link
     * java.lang.String#valueOf(float)}</code> is translated into bytes
     * according to the platform's default character encoding, and these bytes
     * are written in exactly the manner of the <code>{@link #write(int)}</code>
     * method.
     *
     * @param      f   The <code>float</code> to be printed
     * @see        java.lang.Float#toString(float)
     */
    public void print(float f) {
        write(String.valueOf(f));
    }

    /**
     * Print a double-precision floating-point number.  The string produced by
     * <code>{@link java.lang.String#valueOf(double)}</code> is translated into
     * bytes according to the platform's default character encoding, and these
     * bytes are written in exactly the manner of the <code>{@link
     * #write(int)}</code> method.
     *
     * @param      d   The <code>double</code> to be printed
     * @see        java.lang.Double#toString(double)
     */
    public void print(double d) {
        write(String.valueOf(d));
    }

    /**
     * Print an array of characters.  The characters are converted into bytes
     * according to the platform's default character encoding, and these bytes
     * are written in exactly the manner of the <code>{@link #write(int)}</code>
     * method.
     *
     * @param      s   The array of chars to be printed
     *
     * @throws  NullPointerException  If <code>s</code> is <code>null</code>
     */
    public void print(char s[]) {
        write(s);
    }

    /**
     * Print a string.  If the argument is <code>null</code> then the string
     * <code>"null"</code> is printed.  Otherwise, the string's characters are
     * converted into bytes according to the platform's default character
     * encoding, and these bytes are written in exactly the manner of the
     * <code>{@link #write(int)}</code> method.
     *
     * @param      s   The <code>String</code> to be printed
     */
    public void print(String s) {
        if (s == null) {
            s = "null";
        }
        write(s);
    }

    /**
     * Print an object.  The string produced by the <code>{@link
     * java.lang.String#valueOf(Object)}</code> method is translated into bytes
     * according to the platform's default character encoding, and these bytes
     * are written in exactly the manner of the <code>{@link #write(int)}</code>
     * method.
     *
     * @param      obj   The <code>Object</code> to be printed
     * @see        java.lang.Object#toString()
     */
    public void print(Object obj) {
        write(String.valueOf(obj));
    }


    /* Methods that do terminate lines */

    /**
     * Terminate the current line by writing the line separator string.  The
     * line separator string is defined by the system property
     * <code>line.separator</code>, and is not necessarily a single newline
     * character (<code>'\n'</code>).
     */
    public void println() {
        newLine();
    }

    /**
     * Print a boolean value and then terminate the line.  This method behaves
     * as though it invokes <code>{@link #print(boolean)}</code> and then
     * <code>{@link #println()}</code>.
     *
     * @param x the <code>boolean</code> value to be printed
     */
    public void println(boolean x) {
        synchronized (lock) {
            print(x);
            println();
        }
    }

    /**
     * Print a character and then terminate the line.  This method behaves as
     * though it invokes <code>{@link #print(char)}</code> and then <code>{@link
     * #println()}</code>.
     *
     * @param x the <code>char</code> value to be printed
     */
    public void println(char x) {
        synchronized (lock) {
            print(x);
            println();
        }
    }

    /**
     * Print an integer and then terminate the line.  This method behaves as
     * though it invokes <code>{@link #print(int)}</code> and then <code>{@link
     * #println()}</code>.
     *
     * @param x the <code>int</code> value to be printed
     */
    public void println(int x) {
        synchronized (lock) {
            print(x);
            println();
        }
    }

    /**
     * Print a long integer and then terminate the line.  This method behaves
     * as though it invokes <code>{@link #print(long)}</code> and then
     * <code>{@link #println()}</code>.
     *
     * @param x the <code>long</code> value to be printed
     */
    public void println(long x) {
        synchronized (lock) {
            print(x);
            println();
        }
    }

    /**
     * Print a floating-point number and then terminate the line.  This method
     * behaves as though it invokes <code>{@link #print(float)}</code> and then
     * <code>{@link #println()}</code>.
     *
     * @param x the <code>float</code> value to be printed
     */
    public void println(float x) {
        synchronized (lock) {
            print(x);
            println();
        }
    }

    /**
     * Print a double-precision floating-point number and then terminate the
     * line.  This method behaves as though it invokes <code>{@link
     * #print(double)}</code> and then <code>{@link #println()}</code>.
     *
     * @param x the <code>double</code> value to be printed
     */
    public void println(double x) {
        synchronized (lock) {
            print(x);
            println();
        }
    }

    /**
     * Print an array of characters and then terminate the line.  This method
     * behaves as though it invokes <code>{@link #print(char[])}</code> and then
     * <code>{@link #println()}</code>.
     *
     * @param x the array of <code>char</code> values to be printed
     */
    public void println(char x[]) {
        synchronized (lock) {
            print(x);
            println();
        }
    }

    /**
     * Print a String and then terminate the line.  This method behaves as
     * though it invokes <code>{@link #print(String)}</code> and then
     * <code>{@link #println()}</code>.
     *
     * @param x the <code>String</code> value to be printed
     */
    public void println(String x) {
        synchronized (lock) {
            print(x);
            println();
        }
    }

    /**
     * Print an Object and then terminate the line.  This method behaves as
     * though it invokes <code>{@link #print(Object)}</code> and then
     * <code>{@link #println()}</code>.
     *
     * @param x the <code>Object</code> value to be printed
     */
    public void println(Object x) {
        synchronized (lock) {
            print(x);
            println();
        }
    }


}
